Question

Why is x^2+1 divisible by 10 is x^2+1 has a 3 or 7 in the one's place?

Answer 1

So if I plug in a 3 or 7, or any number with a 3 or 7 in the one's place, like 3,7,13,17,23,27 etc... x^2+1 is divisible by 10. Why?

Answer 2

Is there a reason for this?

Answer 3

any number is divisible by \(10\) if the last digit is 0

Answer 4

\( (x^2+1)\) the last digit of this expression will be \(0\) only when the last digit of \(x^{2}\) is \(9\) and \(3^{2}=9\) and \(7^{2}=49\)

Answer 5

Yes makes sense. Thanks :) .